I didn’t think I could be surprised by this book. After all, I dived in two books later at ‘Gaudy Night’ so I already know Harriet Vane and I thought I understood her complex relationship with Peter Wimsey.

Yet the book did surprise me. Firstly because I saw no more of Harriet Vane than Wimsey did, which isn’t much. Second, because the investigation to clear Vane’s name and unmask the real killer is carried out not by Wimsey but by clever, resourceful women working for him. The final surprise was Wimsey himself. He carries a great deal more trauma with him than I had understood and his attraction to Vane goes beyond charmingly eccentric to desperate and obsessive until it seems that his love for her may be the ‘Strong Poison’ of the title. It took me a long time to see that, from Wimsey’s point of view, he is not rescuing Vane, she is rescuing him.

I’m not a fan of insta-love. It seems to me to be either a lazy plot device or a shared delusion. And yet, I could immediately see why Wimesy fell for Vane. She’s tough, bright, educated, independent, honest with herself and capable simultaneously of dignity, humour and kindness. How could you not love that?

She is a woman under great pressure and with little hope and has just met for the first time an eccentric man who seems not to be playing with a full deck yet when Wimsey asks if he may call on her again in prison, she replies:

‘I will give the footman orders to admit you,’ said the prisoner, gravely; ‘you will always find me at home.’

Wimsey presents himself to Vane with all the grace of a new-born foal trying to learn to use its legs, but that’s part of the fun. If you’re going to propose to a woman the first time that you meet her, and that first time is when she’s in prison for murder, then you go in knowing that, if you are to be honest, you cannot fail also to be absurd.

Yet, even in the midst of his awkwardness, the real man comes through by asking one simple question. In his effort to assess the relationship between Vane and her former lover, he asks:

‘Were you friends?’

The question says a great deal about Wimsey’s values and his insight into people. Vane’s instant reply of ‘No.’ holds in it the doom of her relationship with her former lover and the ‘repressed savagery’ with which she delivers it explains a great deal about her and how she came to be in her current situation.

Given how clever and insightful Wimsey is and given that he has already said to Vane,

‘you’ll understand that I’m not really such an ass as I’m looking at present.’

I’m a little unsure how much to take the charm of his marriage pitch to Vane at face value.

To a woman whose lover disdained friendship, he says

‘I’d like somebody I could talk sensibly to, who would make life interesting. And I could give you a lot of plots for your books, if that’s any inducement.’

To a woman who has won her financial independence by writing fiction, he says that he would like a wife who writes books because

‘…it would be great fun. So much more interesting than the ordinary kind that is only keen on clothes and people. Though, of course, clothes and people are all right too, in moderation.’

To a woman who has had her sexual history used against her in court and who reminds him that she has had a lover, he responds:

‘Oh, yes. So have I, if it comes to that. In fact, several. It’s the sort of thing that might happen to anybody.’

These remarks sound honest and innocent and most likely are both but are they not also artfully knowing and carefully persuasive?

If I were Harriet Vane, I’d want to believe in Wimsey’s honesty but I’d find it hard to set aside his careful curation of his character.

After the initial encounter between Wimsey and Vane, the book stumbles a little as the unassailability of the case against Vane is established, one slow step at a time. Fortunately, that is the last problem with pace because, after that, I was introduced to The Cattery and its inmates and everything took off.

I really loved the idea of Wimsey funding That Cattery, a private agency, staffed by competent, resourceful woman that, for one reason or another, society has no place for, to track, trap and offer up for prosecution, men who seek to abuse or deceive vulnerable women. Some of the best parts of the novel come from watching two of these women figure out how to insert themselves into a new environment and then farm it for information by whatever means necessary.

The qualms I had about Wimsey, I set aside when I saw how he worked with these women: establishing trust, setting direction, providing resources, promising support but never telling them how to do what needs to be done.

The plot is cunning but not so arcane that the resolution came as a surprise but how the resolution was achieved was what made me read a little longer than I had intended to each time.

I liked that I got to see Wimsey in so many settings, with his family, his colleagues and friends, his valet, his underworld associate sand the Cattery inmates. He is a complex man whose most consistent characteristics seem to be a strong independent will, a disregard for rules, an instinct for kindness and a deep unease at showing people who he really is. Which explains a lot about his attraction to Vane.

I particularly liked the low-key ending of the story. It left me hungry for the next book.